1. Field of the Invention
The present invention relates to a magnetic recording medium which could be used for video or audio, for example, and, more particularly, to a medium having an in-plane magnetizable film on its base.
2. Description of Related Art
In the conventional thin-film magnetic recording media, there are known some examples with magnetic thin films of alloys such as CoNi, CoP, CoPt and so forth which have isotropic properties with in-plane magnetization. Such magnetic thin films of CoNi and CoP have hard magnetic characteristics which are obtained by utilizing a columnar structure, including a saturation flux density Bs of about 10 kG and a coercive force Hc of about or less than 1 (kOe). Meanwhile, relative to the magnetic thin film of CoPt, an example is disclosed in Japanese Patent Laid-open No. 58 (1983)-200513, wherein the film indicates a great coercive force Hc of more than 1.5 (kOe) in a film thickness of less than 300.ANG., but in accordance with an increase of the film thickness, the coercive force Hc is rendered as low as 700 (Oe) or so although the saturation flux density Bs remains about 10 kG.
There are also known some other magnetic thin films of alloys such as CoCr, CoMo, CoV and CoRu each of which are adapted for perpendicular magnetization. Although a large coercive force is attained in each of such magnetic thin films if the base temperature is raised to 150.degree. C. or so during deposition of the magnetic layer by sputtering or the like, the coercive force is as small as 300 (Oe) or so when the base temperature at the time of layer deposition is kept at room temperature. Consequently, it is impossible to use a low-cost base of polyethylene terephthalate (PET) which has low heat resisting properties.